Purpose: To determine the associations among diabetes status, Metformin administration and prostate cancer (PCA) detection at biopsy in Chinese population. Methods: A case-control study was conducted among a prospectively enrolled prostate biopsy cohort of 518 patients from Jan 2013 to Dec 2014 at our institute. Diabetes status and Metformin administration were determined through medical records and self-report. Different clinical characteristics were registered and compared among differ-ent groups. Univariate and multivariate logistic regression analyses were performed to evaluate the effects of diabetes status and Metformin administration on the detection of overall as well as high-grade PCA at biopsy. Results: PCA was detected in 229 (44.2%) men, and high-grade PCA (Gleason score ≥8) was detected in 65 (12.5%) men. Diabetes was observed in 96 men, and 28 of them were administered with Metformin. Both overall and high-grade cancer detection rates were significantly higher in diabetic patients (p<0.001). In multivariate analysis, diabetes status was a risk factor for high-grade cancer detection (OR 7.699, 95%CI 3.483-17.020, p<0.001), but not for total PCA detection (OR 1.774, 95%CI 0.831-3.787, p=0.138). Meanwhile, Metformin administration was proved to be a protective factor for high-grade disease (OR 0.420, 95%CI 0.201-0.879, p=0.021) in multivariate analysis, while no correlation was detected with overall cancer detection (OR 0.786, 95%CI 0.172-3.593, p=0.756). Conclusions: Diabetes status was positively associated with biopsy-mediated high-grade PCA detection in Chinese population, while the positive association would be partly compromised by Metformin administration.